import java.util.*;
/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: tao
 * Date: 2023-11-05
 * Time: 13:34
 */
public class Test {
    public static void main(String[] args) {
        Queue<String> queue = new LinkedList<>();
        Scanner sc = new Scanner(System.in);
        int t = sc.nextInt();
        int c = sc.nextInt();
        int s = sc.nextInt();

        int x = (int)(((s-c) * 1.0) / c * t);

        System.out.println(x);
    }
    public static void main3(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int s = scanner.nextInt();
        int t = scanner.nextInt();

        if(s < t) {
            System.out.println(t - s);
        }
        if(s > t) {
            System.out.println(7 - (s - t));
        }
    }
    public static void main2(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String A = scanner.nextLine();

        if(A.equals("jiandao")) {
            System.out.println("bu");
        } else if(A.equals("shitou")) {
            System.out.println("jiandao");
        } else {
            System.out.println("shitou");
        }
    }
    public static void main1(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        HashSet<String> set = new HashSet<>();
        for(int i = 0; i < n; i++) {
            String str = scanner.next();
            set.add(str);
        }

        List<String> list = new LinkedList<>();
        for(String str : set) {
            list.add(str);
        }

        int i = 0;
        while (list != null) {
            System.out.println(Arrays.toString(new String[]{list.get(i)}));
        }
    }
}
